Amikacin is often preferred over gentamicin in hospitals with high rates of gentamicin-resistant Gram-negative infections because:
- A Amikacin is not transported into bacterial cells by modifying enzymes
- B Amikacin has fewer sites vulnerable to aminoglycoside-modifying enzymes ✓
- C Amikacin binds to the 50S ribosomal subunit instead of the 30S subunit
- D Amikacin is not a substrate for bacterial efflux pumps
Correct answer: B. Amikacin has fewer sites vulnerable to aminoglycoside-modifying enzymes
Explanation
Amikacin was semisynthetically designed by adding an L-hydroxyaminobutyryl group to kanamycin, which sterically shields most positions targeted by aminoglycoside-modifying enzymes. It therefore retains activity against many strains resistant to gentamicin and tobramycin. Like all aminoglycosides it still binds the 30S subunit, and efflux pumps are not the relevant resistance mechanism for this class. Enzymatic modification remains possible but far less frequent for amikacin.
Reference: Katzung Basic and Clinical Pharmacology, 16th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.